This paper presents two methods for detection DS CDMA signals hidden in the noise are described. The proposed methods are based on analysis of an averaged spectrum of the signal and an averaged spectrum of signal raised to the power 2n. These methods are difficult to use when narrowband signals are presented in an analysing frequency band. Influence of narrowband signals for the DS CDMA signals detection is shown. Simulation experimental results are provided to illustrate the approach. Experimental results with filtering interferences in the time domain and the in frequency domain are presented.